Rotary machines



sept. 15,1970 P; G. WARE 3,528,757

ROTARY MACHINES Filed June 28, 1968 :WEA/TDR PETER GL WERE HTTDRVEyS United States Patent O U.S. Cl. 418-107 9 Claims ABSTRACT F THE DISCLOSURE A rotary machine comprising a rotor member supported within a chamber, an adjustment screw on the chamber being engageable with an abutment on the rotor member for adjustment of the axial position of the rotor member.

This invention relates to rotary machines, for example rotary vane pumps or duid-pressure operated motors, of the kind in which a rotor member is supported within a chamber and has an end face which is intended to run in close proximity to an end wall of the chamber so as to provide a substantially fluid-tight seal.

One object of the invention is to provide a rotary machine having adjustable means for controlling the clearance between a rotor member and an associated end wall.

According to one aspect of the invention, a rotary machine comprises a chamber, a rotor member supported within the chamber and having an end face arranged to move in close proximity to an end wall of the chamber and an adjuster means comprising a first abutment associated with the end wall and aligned with the axis of rotation of the rotor member and a second abutment associated with the rotor member and engageable with the first abutment, the first abutment being axially movable relative to the end wall to edect adjustment of lthe axial position of the rotor member.

According to a further aspect of the invention a rotary vane pump comprises a pump chamber, a movable vane rotor member supported within the chamber and having an end face arranged to move in close proximity to an end wall of the chamber and an adjuster means comprising a first abutment associated with the end wall and aligned with the axis of rotation of the rotor member and a second abutment associated with the rotor member and engageable with the first abutment, the rst abutment being axially movable relative to lthe end wall to effect adjustment of the axial position of the rotor member.

Preferably the first abutment is in the form of a hardened steel surface formed by the end surface of an adjust ment screw which passes through a screw-threaded bore in the end wall in line with the axis of the rotor member, the adjustment screw being lockable in any desired axial position by means of a locknut engaging the screw on the outer side of the end lwall. The second abutment may take the form of a hardened steel button pressed into a central recess in the end face of the rotor member.

One embodiment of the invention will now be described, by way of example.

A rotary vane vacuum pump comprises a cylindrical housing 1 assembled from a pair of generally fiat radially extending end walls 2, 3` and a cylindrical body portion '4. The housing is mounted on the casing 5 of an electric motor by means of mounting bolts 6 which also serve to secure the end walls 2, 3 one on each side of the cylindrical body portion 4. The shaft 7 of the electric motor projects, through a low friction bush 8 located in an opening formed at an olf-centre position in the end Wall 3 of the housing, into a cylindrical chamber 9 within the housing.

A movable vane rotor 10 is keyed to, and locked in a 3,528,757 Patented Sept. 15, 1970 fixed axial position on the shaft 7, and is provided with four circumferentially spaced, tangentially slidable vanes 1'1' for engagement with the cylindrical walls of the body portion 4, the axial length of the rotor being slightly less than the axial length of the chamber 9 within which it is housed so as to enable the rotor to rotate freely within the housing.

Inlet and delivery ports (not shown) are formed in the axially outer end wall 2 of the housing, that is, the wall remote from the motor, and this end wall constitutes a cylinder head.

The general arrangement and operation of the pump is conventional, the off-centre location of the rotor 10 resulting in the portion of the chamber 9 above the shaft 7 as seen in the drawing being of smaller volume than the portion of the chamber below the shaft. The inlet port opens into the latter portion of the chamber, and fluid entering through the inlet port is trapped between successive vanes of the rotor and its pressure raised as it is carried round to the smaller volume portion of the chamber where the fluid is allowed to discharge through the delivery port The axially outer end wall 2 of the housing 1 has a screw-threaded bore y12 formed in axial alignment with the shaft 7 of the electric motor, and this bore contains, in screw-threaded engagement with the bore, a hardened steel adjustment screw 13 having a part-spherical surface 14 on its axially inner end which projects into the chamber 9 and constitutes a first abutment. The adjustment screw is provided with a screwdriver slot 15 in its axially outer end and can be locked in a fixed axial position by means of a locknut 16 on the outer surface of the end wall 2.

The axially outer end face of the rotor is formed with a central recess 17 in which a hardened steel button 18 is located the button having an axially outwardly facing partspherical surface 19 which is engageable with the corresponding surface 14 formed on the adjustment screw 13, the button constituting a second abutment which is engageable with the first abutment to control the mini- 'mum clearance between the axially outer end face of the rotor 10 and the axially outer end wall 2 of the housing 1.

In setting up the vacuum pump described above the rotor 10 is locked to the motor shaft 7 in a position which will provide, in the axially innermost position permitted by the end float of the motor shaft, a nominal clearance of 0:0015 of an inch between the axially inner end face of the rotor and the associated end wall 3 of the housing `1, and a nominal clearance of 0 00'4 of an inch between the axially outer face of the rotor and the axially outer end wall 2, which constitutes the cylinder head.

The cylinder head is then secured in position and the motor is energised to drive the pump. While the pump is being driven the minimum running clearance between the rotor 10 and the cylinder head 2 is adjusted as follows: the adjustment screw 13 is tightened until the power consumed by the motor in driving the pump begins to rise sharply indicating that the motor shaft 7 is being retarded by friction in its bearings brought about by the end loading applied by the screw. ln this position of the screw the motor shaft is in its axially innermost position, and to establish a predetermined minimum clearance of, say, 0.1003 of an inch between the axially outer end face of the rotor and the cylinder head it is then necessary to slacken the adjustment screw by turning it through an appropriate angle depending on the pitch of its screw thread to move it axially through a distance of 0.001 of an inch. The screw is then locked. in position by the locknut 16.

As a consequence if the accurate control afforded by the adjustment device described above the rotor can safely be set to operate at a smaller clearance from the cylinder head than has 'been the practice in the design of conventional vacuum pumps. However, there remains a possibility that deflection of the shaft 7 may cause tip contact between the radially outer portion of the rotor Varies 11 and the cylinder head face. To reduce the load imposed on the rotor when this occurs, the edges of the vanes may be roughened by a fine grooving technique, which may be supplemented by vapour blasting so that when contact with the cylinder head occurs the crests between the grooves are rubbed down to the extent necessary to avoid local high loading. The edges of the vanes may alternatively be broken up by coining to give a reticulated pattern.

A further way in which seizure or scuifing between the rotor and the cylinder head may be avoided lies in the use of a coating of a dry lubricant such as a polytetraiiuorethylene or graphite emulsion, or molybdenum disulphide in a suitable bonding agent. A layer of low-friction metal such as lead or lead/tin, lead/indium alloy may alternatively be applied either to a plain or a grooved rotor end face.

Having now described my invention, what I claim is:

1. A rotary machine comprising a chamber, a rotor member supported within the chamber and having an end face arranged to move in close proximity to an end wall of the chamber and an adjuster means comprising a Iirst abutment associated with the end wall and aligned with the axis of rotation of the rotor member and a second abutment mounted on the rotor member and engageable with the first abutment, the iirst abutment being axially movable relative to the end wall to effect adjustment of the axial position of the rotor member.

2. A rotary vane pump comprising a pump chamber,

va movable vane rotor member supported within the chamber and having an end face arranged to move in close proximity to an end Wall of the chamber and an adjuster means comprising a first abutment associated with the end wall and aligned with the axis of rotation of the rotor member and a second abutment mounted on the rotor member and engageable with the first abutment, the iirst abutment being axially movable relative to the end wall to effect adjustment of the axial position of the rotor member.

3. A rotary vane pump according to claim 2 wherein the abutments comprise hardened steel surfaces.

4. A rotary vane pump according to claim 2 wherein the iirst abutment comprises a hardened surface formed by the end surface of a steel adjustment screw which engages a threaded bore in themend wall of the chamber, the screw being arranged with its axis aligned with the axis of rotation of the rotor member.

5. A rotary yvane pum-p according to claim 2 wherein at least a portion of the end face of the rotor member is roughened.

6. A rotary vane pump according to claim 5 wherein the roughening is in the form of fine grooves.

7. A rotary vane pump Iaccording to claim 2 wherein at least a portion of the end face of the rotor member is covered with a layer of a dry lubricating material.

8. A rotary vane pump according to claim 2 wherein at least a portion of the end face of the rotor member is covered with a layer of a low friction metal.

9. A rotary vane pump comprising a pump chamber, a movable vane rotary member supported within the chamber and having an end face arranged to move in close proximity to an end wall of the chamber and an adjuster means comprising a first abutment associated with the end `wall and aligned with the axis of rotation of the rotor member and a second abutment comprising a hardened steel button pressed into a recess formed in the end face of the rotor member and aligned with the axis of rotation of the member so as to be engageable with the rst abutment, the iirst abutment being axially movable relative to the end wall to effect adjustment of the axial position of the rotor member.

References Cited UNITED STATES PATENTS 2,371,081 3/1945 Tucker et al. 103-136 2,462,481 2/ 1949 Estey 103--136 2,651,453 9/1953 Le Febore et al 230-151 2,850,985 9/ 195 8 Kammerer.

3,104,616 9/ 1963 Peet.

3,327,638 6/1967 Scognamillo 103-136 3,343,782 9/1967 Brewer et al 23o-157 3,429,228 2/ 1969 Stoica 103-136 X 3,439,623 4/ 1969 Dietrich et al. 103--136 X DONLEY I. STOCKING, Primary Examiner W. I. KRAUSS, Assistant Examiner U.S. C1. X.R. 

